Extreme weather events

The extreme weather events tool uses data from DPIRD's extensive weather station network to map extreme temperatures, either below or above a specified threshold. It provides real-time information about the location, duration and severity of frost and heat stress events, to help grain growers manage accordingly to reduce their financial impact.

Spring frosts occasionally cause drastic reductions in crop yield and quality in localised parts of the Western Australian grainbelt. Frost occurs on clear nights in early spring when the air temperature drops to 2°C or less. The amount of damage to crops from frost is influenced by:

the absolute minimum temperature (frost event severity)

how long the temperature remains low (event duration)

the growth stage of the crop (frost causes most damage at and around flowering)

local topography (low-lying areas are more susceptible).

Heat stress is caused by high temperatures and hot dry winds before or during flowering.

Information provided by the tool

This tool allows users to map areas affected by frost or heat stress events, using real time data from the department's weather station network. It can be used to examine events for a single day or night, or for a range of days. The period of time considered can be chosen as:

Day (09:00 to 09:00 the next day) - useful for considering high temperature/heat stress events.

The user can then select the mode and temperature threshold to examine cold or hot events of varying severity.

Single day tab

After clicking on the 'Search' button, the tool will display a map of weather stations that were online on the selected dates. The stations where extreme weather events occurred according to the selected criteria will be overlaid by coloured icons, where the duration of the event is reflected by the icon colours. Below the map, a table lists the stations where events occurred and shows the number of minutes for which the criteria was met, giving an indication of the event duration.

More information is shown when the user clicks on any of the stations where events occurred. Clicking on a station will display a graph of temperature and the number of minutes in each hour that the criteria was met. A table below the graph shows the minimum temperature and the number of minutes below threshold for each hour.

Range of days tab

After clicking on the 'Search' button, the tool will display a map of weather stations that were online on the selected dates. The stations where extreme weather events occurred according to the selected criteria will be overlaid by coloured icons, where the duration of the event is reflected by the icon colours. Below the map, a table lists the stations where events occurred and shows the number of minutes for which the criteria was met, giving an indication of the event duration.

More information is shown when the user clicks on any of the stations where events occurred. Clicking on a station will display a graph of temperature and the number of minutes in each hour the criteria was met. A table below the graph shows the minimum temperature and the number of minutes below threshold for each day in the selected range.